1. Field of the Invention
The present invention relates to an apparatus and a method for correcting image distortion of a rear imaging device, and more particularly, to an apparatus and a method for correcting image distortion of a rear imaging device, which generates a correction model for image correction by applying a tilting angle of a virtual imaging device set according to a plurality of photographed areas depending on a characteristic value of a rear imaging device, and corrects the distortion of the photographed image of the rear imaging device based on the correction model.
2. Description of the Related Art
A rear imaging device of a vehicle provides a image of a rear area which may not be visible to a driver. In particular, the rear imaging device provides the driver with information covering a wider area using a wide-angle lens or a fish-eye lens with a large angle of view. The wide-angle lens has a substantially shorter focal distance than that of a standard lens and has an angle of view of about 60 through 120 degrees. The fish-eye lens as an ultra wide-angle lens has an angle of view of about 180 degrees or more. In particular, the fish-eye lens is manufactured so that uniform brightness and sharpness are maintained with respect to the overall angle of view of about 180 degrees or more by generating a cylinder-shaped distortion. The fish-eye lens photographs an object focusing on the center of the object and distorts the surrounding areas. In other words, the fish-eye lens may obtain an image of a wide area. In particular, with regards to a vehicle, much more information of the rear area of the vehicle may be provided to a driver by using the fish-eye lens. In addition, when the fish-eye lens is applied to an image phone, it may be possible to capture a wide viewing angle at a short distance.
However, an image photographed through a rear imaging device having a wide-angle lens or a fish-eye lens may be distorted. In particular, a degree of the distortion may be increased from the center of the image toward a periphery thereof. Accordingly, the distorted image provided through the rear imaging device does not accurately depict the photographed area. Thus, the driver may not correctly recognize the state of the rear of the vehicle.
As a method of correcting such lens distortion, a correction lens may be installed to correct the lens distortion or a software may be used to correct the distorted image. Since installing an additional correction lens may increase a manufacturing cost of the imaging device conventionally the software method has been used.
In the related art, it may be possible to select a grid type test pattern and to manually correct a distortion correction coefficient of an imaging device until the distortion-free image is displayed. In other words, changing a contour of the image by radially dragging the corner of the test image from the center of the image and correcting contents of the changed image are repeatedly performed until the distortion is removed. In another related art, the distortion-corrected image may be obtained from the distorted original image by setting a lens distortion variable while receiving any image and increasing or decreasing a range of the distortion variable of the image.
However, according to conventional technology for geometric distortion correction of a digital image, the driver must manually correct the distortion correction coefficient.